Method of bonding paper and composition therefor



Sept. 6, 1955 A. L. MCCONNELL ET AL 2,717,224

METHOD OF souomc PAPER AND COMPOSITION THEREFOR Filed July 20, 1954United States Patent O METHOD OFBONDING PAPER AND COMPOSITION THEREFORAlbert L. McConnell, Morton, and Robert W. Medeiros, Swarthmore, Pa.,assignors to Scott Paper Company, Chester, Pa., a corporation ofPennsylvania Application July 20, 1954, Serial No. 444,673

19 Claims. (Cl. 154-117) The present invention relates to a method ofbonding paper to other materials; and, more particularly, the inventionrelates to a method of bonding temporarily, paper, such as papertoweling, toilet tissue, waxed paper and the like, to other paperbodies, including cardboard. The invention also relates to a noveladhesive for use in accordance with the present method.

There are many instances where it would be desirable temporarily toadhere paper to another body. In the manufacture of rolls of paperproducts, such as paper toweling, toilet tissue, waxed paper, and thelike, a long strip of the paper is wound about a cardboard core ormandrel to provide a roll. To start this winding operation, an adhesiveis applied to the end of the strip or to the cardboard core so that theend of the strip will adhere to the core. Once the winding operation hasbeen started, the bondability of this adhesive is no longer of anyimportance. In fact, it would be highly desirable if the adhesive wouldcompletely lose its bondability so-th'at the last few layers of paperadjacent the core could be easily removed and utilized by the consumer.The'conventional adhesives normally employed, such as glue and starch,dry

to a relatively permanent bond, so that when the paper is removed from,the roll, the last few layers are firmly bonded together and to thecardboard core. In addition, in wrapping paper rolls, such. as rolls oftoilet tissue, it is desirable temporarily to adhere the wrapper to theroll to facilitate picking up the wrapper sheet by the roll. Once theroll is wrapped, adhesion between the roll and wrapper is no longerdesirable.

The permanent bond provided by the above-mentioned conventionaladhesives may be diminished to someextent by the use of plasticizers.However, in such cases, it has been found that the initial tack of thematerial is reduced to a degree such that it becomes unsatisfactory inoperation, particularly on the more recent high speed, continuouswinding equipment where the core is started rotating at high speedbefore the paper is brought into contact therewith, and where a highdegree of tack is required of the adhesive in order thatthe rotatingcore pick up and hold the end of the paper strip at the initiation ofthe winding operation. Other adhesives have been formulated with theview'of providing temporary adhesion of the type mentioned, but thesehave. been found to lack the requisite high initial tack for use in highspeed,lcontinuous winding equipment, and would leave markings on thepaper so that even if the papercould readily be removed its appearancemight discourage .its use. It will be seen that the optimum type ofadhesivefor the aforementioned purposes shouldhave: (1) extremely high.initialtack; (2) completeloss of initial tack withina period of daysafter application to the paper, and (3) aminimum of marks left on thetreated paper within a few days after application. Many'of the foregoingconsiderations also apply in winding other'sheet materials, such asaluminum foil, plastic film, and the like, about a cardboard core,

and it will be seen that thepresent invention is also appli cable to thetemporary adhesion of such materials to the ice it is applied, beingabsorbent, by which, in spite of a very high degree of initial adhesion,the bond is completely lost within a short time after the paper and theother surface have been initially adhered together. 1

Another object of the invention is to provide a method of bonding,temporarily, paper to another paper body, at least one of said papermembersbeing absorbent.

Another object of the present invention is to provide a method ofbonding, temporarily, paper to another paper body, at least one of saidpaper members being absorbent.

Another object of the present invention is to provide a method foradhering paper temporarily to anotherjsnrface whereby, after theadhesive bond is lost, the paper exhibits no adverse marking,transparentization, or the like. a

A further object of the present invention is to provide a novel adhesivecomposition for temporarily adhering paper to another surface,especially to another paper'body, which composition, after applicationto paper and performing its initial bonding function, completely lose sits adhesive properties and leaves no deleterious markings on the papersuch as transparent areas, and the like.

Other objects will become apparent from a consideration of the followingspecification and the claims.

The process of the present invention comprises apply ing to at least oneof the surfaces which are to be adhered together, that is either to thepaper or to the surface to which the paper is to be bonded, or to both,hydrogenated rosin, and then bringing together the surfaces to be bond-ved with the hydrogenated rosin therebetween. For example, in the windingof a long strip of paper, such as paper toweling, toilet tissue, waxedpaper, and the like, onto the cardboard core to make a rolled product,hydrogenated rosin may be applied to the core or to the end of the paperstrip, or to both, following which the end of the paper strip iscontacted with the cardboard core, with the hydrogenated rosin adheringthe end of the paper strip to the cardboard core, and winding the paperstrip thereon until the desired roll has been built up. The process isparticularly applicable for use in the more recent high-speed,continuous winding equipment wherein the core is started rotating beforepicking up theend of the paper strip. The hydrogenated rosin will causethe end of the paper stripto adheresecurely to the rotating cardboardcore so that the paper will notslip from place and the winding operationmay be satisfactorily carried to completion.

The operation of the last-mentioned embodimentwill be more readilyunderstood from a consideration of the drawings in which; v, p

Fig. 1 is a diagrammatic side elevational View of apparatus wherein thehydrogenated rosin is applied to, a rotating core following which an endof a strip of paper is picked up by. and adhered to the rotating coreand wound thereon; and A v Fig. 2 is a diagrammatic elevational viewof aportion of Figure 1 taken along the line-22. n

In accordance with a preferred embodiment of the present invention, whenan absorbent paper sheet is. to be adhered temporarily to anothersurface, a small amount of a finely-divided pigment is included in thehydrogenated pigment will match the color of the paper. While in mostcases, the paper will be white, in which event a white pigment will beemployed, in some instances, such as with tinted toilet tissue, apigment matching the color and shade of the colored paper may beemployed. In addition, in order to render the hydrogenated rosin easilyremovable from the machinery and to disperse it in the paper-makingsystem should it get into that system associated with broke, it is alsopreferred to include in the hydrogenated rosin a small amount of aconventional surface active emulsifying agent. Theses embodiments willbe discussed more in detail hereinafter.

The present invention is based upon the discovery that, althoughhydrogenated rosin possesses an extremely high degree of initial tackwhen first applied to paper so as to enable the paper to become bondedsecurely to another surface, especially to another paper body, the bondinitially provided by the hydrogenated rosin may be destlroyed withoutfurther treatment so that after a period of time the paper may readilybe removed from the surface to which it was adhered initially. After thepaper has been adhered to the surface by means of the tacky hydrogenatedrosin, the hydrogenated rosin migrates away from the original bond lineand through the paper or through the material of which the other surfaceis prepared, or through both, thereby losing its adhesive properties. Ina matter of a few days, the exact number depending upon ambienttemperature conditions, these adhesive properties are completely lost,and the paper may, therefore, readily be separated from the surface towhich it was initially applied. In the winding of a long strip of paperonto a cardboard core, for example, in the preparation of rolls of papertoweling, toilet tissue, waxed paper, and the like, the end of the paperstrip to be wound may readily be adhered to the cardboard core tofacilitate the initiation of the Winding operation. After the windingoperation has been completed and by the time the resulting roll hasreached the consumer, all of the paper on the roll is usable inasmuch asthe last few layers or sheets of paper adjacent to the cardboard corewill not adhere to the core and can readily be removed therefrom. Asstated, the invention is particularly adapted for use on therecently-developed, high-speed, continuous Winding equipment, and animportant feature of hydrogenated rosin in this connection is that itsviscosity can be controlled within a relatively wide range withrelatively small changes in temperature. Thus, for ease of applicationto the rotating cardboard core, the hydrogenated rosin may be warmed toa point where it is relatively fluid and then applied to the rotatingcore. Contact wtih the rotating core quickly cools the material, rapidlyincreasing its viscosity so that it will not be thrown, by centrifugalforce, from the core.

Although the hydrogenated rosin may transparentize the paper to which itis applied and the paper adjacent the area of initial bonding throughmigration, the inclusion of the opacifying agent, in accordance with apreferred embodiment of the invention, prevents this transparentization.In fact, any markings remaining on the paper through pick-up andmigration of the opacifying agent-containing hydrogenated rosin will be,to the consumer, very slight if, indeed, they are at all perceptible.Although the hydrogenated rosin is not readily soluble in water, it canreadily be removed from equipment during cleaning operations and canreadily be dispersed in the paper making system, when a conventionalsurface active emulsifying agent is included therein in accordance withanother preferred embodiment of the invention.

Since destruction of the bond is dependent upon migration of thehydrogenated rosin, either the paper or the surface to which the paperis adhered, or both, will be absorbent. When the paper is ordinary paperwhich is conventionally produced in roll form, such as paper toweling,toilet tissue, and the like, it is sufficiently absorbent to permitmigration of the hydrogenated rosin thereinto. When a less absorbent ornon-absorbent sheet such as waxed paper, plastic film or aluminum foilis to be adhered to a cardboard core for winding, reliance is placed onthe cardboard core to absorb the hydrogenated rosin. Of course, inwinding paper toweling, toilet tissue and the like on a cardboard core,the hydrogenated rosin migrates into both the paper and the core.

Hydrogenated rosin is the product of converting rosin to alcohol form byreduction. Hydrogenated rosin, or hydroabietyl alcohol as it is knowntechnically, is a colorless, tacky, viscous liquid at room temperature.The viscosity of the material ranges from about 400 poises at 40 C. toabout 0.4 poises at 100 C. This range of viscosity is advantageous as apractical matter since it may be controlled by temperature as mentionedpreviously. Hydrogenated rosin is actually composed of a mixture ofdehydroabietyl, dihydroabietyl and tetrahydroabietyl alcohols plus aminor proportion, usually less than about 20%, of a non-alcoholfraction. Under normal conditions, the material will neither oxidize norpolymerize and. hence, through plastic flow it will migrate through thepaper or through the surface to which the paper is applied therebylosing its initial bonding power. A typical hydrogenated rosin which hasbeen found to be highly advantageous in accordance with the presentinvention is Abitol, a product of the Hercules Powder Co. The alcoholicfraction of this material contains between about. 14 and about 23% ofdehydroabietyl alcohol, between about 36 and about 39% of dihydroabietylalcohol and between about 38 and about of tetrahydroabietyl alcohol. Thenon-alcohol fraction makes up an average of about 15% of thehydrogenated rosin.

The liquid portion of the adhesive employed in accordance with thepresent invention consists essentially of the hydrogenated rosin, and ifsmall amounts of an organic solvent such as xylene, carbontetrachloride, ethylene dichloride, and the like, are included for anyreason, it is preferred that such material be in an amount less thanabout 20% based on the weight of the hydrogenated rosin.

As stated, in order to prevent transparentization of the paper to whichthe hydrogenated rosin adhesive is applied, it is preferred to includein the hydrogenated rosin a small amount of an opacifying agent. Suchopacifying agents may be any finely-divided, inert inorganic material,the color and shade of which, will match or correspond to that of thepaper. Such materials will disperse in the hydrogenated rosin andmigrate with it through the paper to mask the transparentization effectwhich would ordinarily be produced by the hydrogenated rosin. Whilethere is a wide variety of materials available for this purpose,titanium dioxide is particularly advantageous. Since the main functionof the opacifying agent is to mask the transparentization occasioned bythe hydrogenated rosin, the amount thereof employed may vary widelydepending upon the results desired. In general, between about 1 andabout 10%, by weight, based on the weight of hydrogenated rosin, will beemployed.

To render the adhesive easily removable from the equipment by a cleaningoperation involving water and to render the adhesive readily dispersablein case it should get into the paper-making system, it is preferred toinclude in the adhesive composition a small amount of a surface activeemulsifying agent. Any conventional surface-active agent may be used forthis purpose so long as it is compatible with and dispersible in theremainder of the composition to form a homogeneous mixture. The agentmay be cationic, anionic or non-ionic. Examples of anionicsurface-active agents in the form of watersoluble salts are: soaps, suchas potassium palmitate, triethanolamine oleate, morpholine stearate,sodium laurate, and ammonium myristate; alkyl benzene sulphonates, suchas sodium dodecyl-, keryl-, or tridecyl-benzene sulphonates; alkyldiphenyl sulphonates, such as sodium butyl diphenyl sulphonate; alkylnaphthalene sulphonates, such as sodium diisopropyl naphthalenesulphonate, ammonium diamyl naphthalene sulphonate, sodium monononylnaphthalene sulphonate, sodium isopropyl isobutyl naphthalenesulphonate, and sodium dinonyl naphthalene sulphonate; sulphatedaliphatic alcohols such as sodium hexadecyl sulphate, sodium oleylsulphate, triethanolamine dodecyl sulphate, sodium 3,9-diethyl6-tridecanol sulphate, sodium 2-methyl 7-ethyl 4-undecanolsulphate, and sodium 2-ethyl l-hexanol sulphate; sulphated andsulphonated fatty oils, acids or ester, such' as the sodium salt ofsulphonated castor oil, the sodium salt of sulphated red oil, the sodiumsalt of sulphonated butyl oleate, and the sodium salt of sulphonatedisopropyl oleate; alkyl sulpho phthalates, such as sodium hexadecylsulpho phthalate; sulphated amides, such as sulphated hydroxyethyllauramide and sulphated hydroxy-isopropyl palmitamide; sodium salt oflauryl sulpho acetate; sodium salt of dioctyl sulphosuccinate; sodiumsalt of oleyl methyl tauride; sodium salt of sulphonated dodecylbenzoate, and the like. Examples of non-ionic active agents are: partialesters of polyhydric alcohols, such as nonaethylene glycol monolaurate,and tricosaethylene glycol: monolaurate; condensation products of alkylphenols with ethylene oxide such as the reaction product of isooctylphenol with 12 ethylene oxide units; condensation products of alkylthiophenols with to 15 ethylene oxide units; condensation products ofhigher fatty alcohols with ethylene oxide such as the reaction productsof oleyl alcohol with 10 to 15 or more ethylene oxide units; ethyleneoxide addends of monoesters of hexahydric alcohols and inner ethersthereof such as sorbitan monolaurate, sorbitol monooleate, sorbitanmonopalmitate and mannitan monopalmitate, the non-ionic reactionproducts of fatty acids, or their derivatives, with at least twomolecules of hydroxylated amines as described in Patent No. 2,089,212;and the like. Examples of cationic surface-active agents are: salts ofprimary, secondary and tertiary amines, such as oleyl amine acetate,dodecyl amine acetate, dioctyl amine lactate, stearoyldiethanolamineacetate, and dilauroyl triethylene-tetramine diacetate; and quaternarysalts, such as lauryl pyridinium bromide, octodecyl ethyl morpholiniumchloride, lauroyl-oxyethyl di- (hydroxy ethyl) ethyl ammonium ethylsulphate, oleyl-oxyethyl trimethyl ammonium ethyl sulfate; oleyloxyethyltrimethyl ammonium chloride, and the like. The ethylene oxide addends ofmonoesters of hexahydric alcohols and inner ethers thereof, especiallysorbitan monopalmitate, are particularly advantageous.

The amount of emulsifying agent incorporated in the adhesive mixture mayvary widely. In addition to facilitating removal of the hydrogenatedrosin from the equipment and dispersion thereof in the paper-makingsystem, the surface active agent may be used as a diluent or extender orto adjust the viscosity of the hydrogenated rosin especially tofacilitate migration during colder weather. In general, between about 1and about by weight, based on the weight of hydrogenated rosin, will besuitable, and preferably between about 5 and about 15% will be used.

In preparing the adhesive composition of the present invention, in theevent that an opacifying agent or an emulsifying agent, or both, are tobe included in the composition, these materials, or any one of them, maymerely be mixed with the hydrogenated rosin. To facilitate mixing, thehydrogenated rosin is preferably heated such as to about 150 F. toreduce its viscosity.

In adhering paper in accordance with the process of the invention, theadhesive composition may be applied either to the paper or 'to thesurface to which the paper is to be adhered, or to both. To facilitatehandling and application of the adhesive composition it may be warmed,such as to 120 150 F. in order to reduce its viscosity, or its viscositymay be adjusted by including in the composition a small amount of asolvent of the type mentioned above or by means of the surface activeagent. In the preparation of rolled paper products, for example, theadhesive composition is merely applied to the end of a strip ation, theadhesive will migrate through the paper layers and into the coardboardcore gradually losing its adhesive effect until by the time the roll hasreached the consumer the bond between the paper and the core iscompletely lost.

V The drawings illustrate operation of portions of representativeautomatic winding equipment of the type mem-' tioned above in carryingout the present invention. In Figure 1, the hydrogenated rosincomposition 1 is retained in vessel 2. 3 represents one of a pluralityof applicator wheels mounted on rotating axle 4. The axle and wheelassembly rotate counter clockwise 5 is a core, such as a cardboardcylinder, mounted on rotating mandrel 6. Mandrel 6 and core 5 rotateclockwise; 7 is a similar rotating core and mandrel assembly which hasalready had the hydrogenated rosin composition applied thereto, and istravelling, in a clockwise orbit as shown, toward the paper-pickupposition. 8 is a similar rotating core and mandrel assembly which haspassed the paperpickup position and upon which paper sheet 9 is beingwound into a roll. Paper sheet 9 is fed from bed roll 10. As is knownthe orbital and rotational movements "of the core-mandrel assemblieswith respect to paper sheet 9 are synchronized such that when a fullroll has been built up on core-mandrel assembly 8, paper sheet 9 is cut,and the free sheet end meets core-mandrel assembly 7. Winding thenbegins on assembly 7. V

In Figure 2 the applicator mechanism of Figure 1 is viewed along line2-2. Hydrogenated rosin composition 1a is retained in vessel 2a.Applicator wheels 3a, mounted on axle 4a, rotate picking up adhesivecomposition It; transferring it in the form of bands 11 to core 5a. Core5a, mounted on mandrel 6a, is shown as cut into sections of the desiredlength along lines 12, each section carrying two bands, 11, of adhesivecomposition in this illustration.- 7 I It will be realized that thedrawings and above description thereof are illustrative only, since, aswill be apparent to those familiar with the art, the deposit of adhesivecomposition may take a wide variety of forms. For instance, each coresection may be provided with one or more than two bands of adhesive, andthe adhesive deposit need not be in the form of continuous bands but maybe discontinuous deposits about the periphery of the core.

The practice of the present process and the preparation of the noveladhesive composition may be more clearly understood from a considerationof the following specific example which is given for the purpose ofillustration only and is not intended to limit the scope of theinvention in any way.

Example Five parts of titanium dioxide, 10 parts of sorbitanmonopalmitate and parts of technical hydroabietyl alcohol are thoroughlymixed together. The resulting adhesive composition, warmed to F., isapplied in two bands about a cardboard core. The end of a strip oftoilet tissue is then adhered to the cardboard core and the core rotatedto wind the tissue about the core. After the roll has been prepared andhas stood for a few days, it is found, upon unrolling the paper, thatthe paper adjacent the cardboard core no longer adheres thereto and mayreadily be removed therefrom. Moreover, the composition leaves markingswhich are only barely perceptible.

Considerable modification is possible in the selection of the variousmaterials employed as well as in the techniques followed withoutdeparting from the scope of the invention.

. We claim:

1. The method of bonding paper temporarily to another surface, at leastone of which members is absorbent, which comprises bringing together thepaper and the surface to which the paper is to be adhered temporarilywith hydrogenated rosin therebetween.

2. The method of bonding paper temporarily to another paper body, atleast one of said paper members being absorbent, which comprisesbringing together the paper members with hydrogenated rosintherebetween.

3. The method of claim 2, wherein said hydrogenated rosin contains asmall amount of a surface active emulsifying agent.

4. The method of claim 2, wherein said hydrogenated rosin contains asmall amount of a finely-divided inert inorganic opacifying agent.

5. The method of claim 4, wherein said hydrogenated rosin also containsa small amount of a surface active emulsifying agent.

6. The method of bonding paper temporarily to cardboard which comprisesbringing together the paper and cardboard with hydrogenated rosintherebetween.

7. The method of claim 6, wherein said hydrogenated rosin contains asmall amount of a surface active emulsifying agent.

8. The method of claim 6, wherein said hydrogenated rosin contains asmall amount of a finely-divided inert, inorganic opacifying agent.

9. The method of claim 8, wherein said hydrogenated rosin also containsa small amount of a surface active emulsifying agent.

10. In the winding of sheet material about a cardboard core in themanufacture of a rolled product, the method of bonding the sheet striptemporarily to the cardboard core to facilitate the initiation of thewinding operation without, however, providing a permanent bond betweenthe sheet and the core, which comprises bringing together one end of thesheet strip and the cardboard core with hydrogenated rosin therebetween.

11. In the winding of a paper strip about a cardboard core in themanufacture of a rolled paper product the method of bonding the paperstrip temporarily to the cardboard core to facilitate theinitiation ofthe winding operationwithrmt, however, providing .a permanent bondbetween theLpaperiand the :cardboard core, which comprises bringingtogether oneend of the paper strip and the cardboard core withhydrogenated rosin therebetween.

12. The method .of claim 11,;wherein said hydrogenated rosin contains asmall amount of a surface active emulsifying agent.

13. The method of claim 11, wherein said hydrogenated rosin contains asmall amount.- of a finely-divided, inert inorganic opacifying agent.

14. The method of claim 13, wherein. said hydrogenated rosin alsocontains a small amount of a surface active emulsifying agent.

15. A composition for. bonding, temporarily, paper to another surface,at least one of which members is absorbent, which consists essentiallyof hydrogenated rosin containing small amounts of -a surface activeemulsifying agent and of a finely-divided, inert, inorganicopacifyingagent. I U

16. The .compositionof claim 15, wherein said surface active emulsifyingagent is sorbitan monopalmitate.

17. The composition of claim 15 wherein said opacifying agent istitanium dioxide.

18. A composition for bonding, temporarily, paperto cardboard whichconsists essentially of hydrogenated rosin containing between about 1and about 10%, by weight, of a finely-divided, inert, inorganicopacifying agent and between about 1 and about 20% of a surface activeemulsifying agent.

19. The composition of claim 18, wherein said opacifying agent istitanium dioxideand, wherein, said surface active emulsifying agent is'sorbitan monopalmitate.

References Citedin the file of this patent UNITED STATES PATENTS

1. THE METHOD OF BONDING PAPER TEMPORARILY TO ANOTHER SURFACE, AT LEASTONE OF WHICH MEMBERS IS ABSORBENT, WHICH COMPRISES BRINGING TOGETHER THEPAPER AND THE SURFACE TO WHICH THE PAPER IS TO BE ADHERED TEMPORARILYWITH HYDROGENATED ROSIN THEREBETWEEN.